The present invention relates to the field of tuning systems including a memory for storing tuning information for television receivers and the like.
Recently, a number of tuning systems including a memory having a plurality of memory locations for storing tuning information in binary format for various channels a viewer may select have been proposed. In some of these tuning systems, the memory includes enough memory locations for each of the channels (e.g., channels 2 through 83 in the United States) assigned to the television broadcast band. Typically, in these tuning systems, the memory is preprogrammed by the manufacturer to store the appropriate tuning information for each of the available channels. Thus, such systems have the advantage that they do not require a user normally unfamiliar with the programming of electronic equipment to program the memory in order to set up the tuning system. Unfortunately, because of the size of the memory utilized in these tuning systems, they are relatively expensive. Therefore, in other tuning systems including a memory, for purposes of economy, the memory only includes a limited number (e.g., 16 to 20) memory locations provided for storing tuning information for a respective number of channels. Since the manufacturer of such tuning systems will not, in general, know the channels which are available in users viewing localities, users will have to perform at least some programming. However, to reduce the amount of user programming required for such tuning systems, some of the memory locations may be preprogrammed by the manufacturer to store information for a certain group of most often available channels (e.g., VHF channels 2-13 in the United States).
At any rate, in a tuning system including a memory, whether all or just some of the memory locations are preprogrammed, it is desirable that the tuning system include provisions for automatically skipping channels which are not preferred by a user because of their reception characteristics or program contents. To this end, some tuning systems having a memory for storing tuning information include a separate memory or memory portion with memory locations associated with respective memory locations for storing tuning information for storing a binary signal having a predetermined binary state to identify when the corresponding memory location for storing tuning information should be skipped. Since the number of memory locations in the channel skipping memory portion is equal to the number of memory locations for storing tuning information, such provisions tend to increase the cost of the tuning system.
Channel skipping provisions may also include apparatus for storing binary signals all having the same predetermined states (i.e., either all "1s" or "0s") in the memory locations corresponding to nonpreferred channels in place of the binary signals representing tuning information thereby obviating the need for a separate channel skipping memory or memory portion. Unfortunately, in such systems, the previously stored tuning information for the nonpreferred channels is eradicated and, as a result, if a user wishes to reinstate a skipped channel when, for example, he moves to a new locality where the reception quality and program content of the skipped channel are acceptable, he must reprogram the tuning information for the skipped channels.
In summary, then, in a tuning system containing a memory having a plurality of memory locations for storing tuning information, it is desirable that apparatus for skipping memory locations containing tuning information for nonpreferred channels be provided and that such apparatus be capable of utilizing a portion of the existing memory for normally storing tuning information to store information for identifying nonpreferred channels, thereby obviating the need for an additional memory or memory portion and operating without permanently eradicating tuning information previously stored in the portion of the memory utilized for identifying nonpreferred channels thereby allowing for the recall of the previously stored information.